The Tory election guru, Sir Lynton Crosby, has warned the Remain camp’s “complacency” risks costing it the referendum, but the Leave side needs “to lift its activity and reach” to get its message across.

The Australian political strategist made the comments in his weekly assessment of the European Union (EU) referendum campaign, on the morning a newly released ORB poll showed slightly increased support for Brexit following President Obama’s visit.

The latest poll shows a two-point drop in support for Remain, to 51 per cent, and a commensurate two point increase for Leave to 43 per cent. However, writing for The Telegraph Sir Lyton warns that while the numbers suggest “a tightening in the race” they are within the margins of error, meaning more time is needed “to see if the question seems increasingly settled.”

Weighting the results by factoring in likely turnout, Remain accounts for 51 per cent of all definite voters, down a point since last week, while Leave position is improved with 46 per cent, an increase of three points.

More tellingly for both campaigns, Sir Lynton notes that voter expectations still overwhelmingly favour a Remain vote in June, writing:

Almost three fifths (57 per cent) of voters still believe the Remain camp will win the day, with only 21 per cent believing the same for Leave and just under a quarter (22 per cent) of people unsure of the outcome. These expectations will have been reinforced by those in the Remain campaign who are claiming that the contest is almost over.

This vast gap in expectation means that the Remain campaign is still largely at risk of voter complacency. Many of their supporters will expect to win the referendum and thus fail to recognise the significance of their own vote.

While complacency could thwart the Remain campaign, Sir Lynton says the Leave side is being hit by an inability to convey its message efficiently. He writes that in terms of voter contact, at least in terms of perception, campaigners favouring Brexit are consistently failing to match the Europhiles, explaining:

Nearly half (45 per cent) of people say they have heard from Remain the most compared with just under a quarter (23 per cent) of those who say they have heard from Leave the most. The Leave campaign needs to lift its activity and reach if its message is to have greater impact.

According to Sir Lynton the ORB poll was conducted over the course of President Obama’s UK visit, suggesting “his view has not (and indeed may not) directly influenced voters”, but he notes that it is likely to contribute “to the overall tone of the campaign and voter’s views that they have heard more from Remain.”

The election-winning pollster urges all sides to up their activity in the remaining eight weeks — “a marathon in campaign terms”, which he says has “barely begun” — concluding:

For now, both camps must continue to stay the course with respect to their messaging and focus on consolidating their base support for the referendum. And given that one in five voters either doesn’t know how they will vote or say they will change their mind, I would be doing all I can to find these people and ensure they are visited, phoned and letterboxed within an inch of their lives right up until polling day.